Ce-mediated molecular tailoring on gigantic polyoxometalate {Mo 132 } into half-closed {Ce 11 Mo 96 } for high proton conduction.

Precise synthesis of polyoxometalates (POMs) is important for the fundamental understanding of the relationship between the structure and function of each building motif. However, it is a great challenge to realize the atomic-level tailoring of specific sites in POMs without altering the major framework. Herein, we report the case of Ce-mediated molecular tailoring on gigantic {Mo 132 }, which has a closed structural motif involving a never seen {Mo 110 } decamer. Such capped wheel {Mo 132 } undergoes a quasi-isomerism with known {Mo 132 } ball displaying different optical behaviors. Experiencing an 'Inner-On-Outer' binding process with the substituent of {Mo 2 } reactive sites in {Mo 132 }, the site-specific Ce ions drive the dissociation of {Mo 2 * } clipping sites and finally give rise to a predictable half-closed product {Ce 11 Mo 96 }. By virtue of the tailor-made open cavity, the {Ce 11 Mo 96 } achieves high proton conduction, nearly two orders of magnitude than that of {Mo 132 }. This work offers a significant step toward the controllable assembly of POM clusters through a Ce-mediated molecular tailoring process for desirable properties.